A gooseneck microphone is used mainly in a state of being erected on a table in conference facilities. To easily direct the microphone at the speaker's mouth, a bendable support pipe (gooseneck) is provided as the support member of microphone.
Usually, the support pipe consists of a combination of a freely bendable pipe having self-shape holding properties, what is called a flexible pipe, and a telescopic pipe, and the position and direction of the microphone can be adjusted freely according to the height of speaker.
A gooseneck microphone of this type having the length-adjustable support pipe is called an adjustable gooseneck microphone. The configuration of the adjustable gooseneck microphone is explained with reference to FIGS. 5A and 5B and FIG. 6. FIG. 5A is a sectional view of the adjustable gooseneck microphone, showing a state in which the support pipe thereof is extended to the maximum length, and FIG. 5B is a sectional view thereof, showing a state in which the support pipe thereof is contracted to the minimum length. FIG. 6 is an enlarged sectional view showing a state in which the microphone cord of the adjustable gooseneck microphone shown in FIG. 5 is connected to the circuit board of an output module section.
Referring to FIGS. 5A and 5B, in the gooseneck microphone, as in a tie clip microphone, a condenser microphone unit 10 and an output module section 30 are configured so as to be separated from each other to make the presence of microphone inconspicuous. The condenser microphone unit 10 is supported at the upper end of a support pipe 20, and the output module section 30 is connected to the lower end of the support pipe 20 via a connector 23.
The condenser microphone unit 10 is provided with a cartridge case (shield case) formed of, for example, aluminum. Although not shown, the cartridge case accommodates a condenser unit including a diaphragm and a backplate and an impedance converter for generating audio signals. Usually, a field effect transistor (FET) is used as the impedance converter.
Since the gooseneck microphone is of an adjustable gooseneck type, the support pipe 20 includes a freely bendable flexible pipe 21 and a telescopic pipe 22 consisting of a metallic pipe for adjusting the length.
In this example, the flexible pipe 21 is separated into a first flexible pipe 21a on the distal end side and a second flexible pipe 21b on the proximal end side, and the telescopic pipe 22 is interposed coaxially therebetween. In some cases, the lower end side of the support pipe 20 consists of the telescopic pipe, and the upper end side thereof consists of the flexible pipe.
The output module section 30 is provided with a cylindrical shield case 31 formed of, for example, a brass alloy. The shield case 31 accommodates a circuit board 32 and an output connector 33. The output module section is also called a power module section.
On the circuit board 32, an audio output circuit (not shown) including a low-cut filter circuit and an amplifier circuit, which are necessary for the function of microphone, is provided. Explaining a portion shown in the figures, electrical parts such as a microphone switch 34 and a feeding transformer 35 are mounted.
As the output connector 33, a three-pin output connector specified in EIAJ-RC5236 “Audio latch lock round type connector” is usually used. Specifically, the output connector 33 has No. 1 pin for grounding, No. 2 pin used as the hot side of signal, and No. 3 pin used as the cold side of signal, and is connected to a phantom power source via a balanced shielded cable, not shown.
The condenser microphone unit 10 and the output module section 30 are connected electrically to each other via a microphone cord 40 inserted in the support pipe 20. As the microphone cord 40, a two-core shielded cable is used which contains a power wire for supplying power to the condenser microphone unit 10, a signal wire for supplying audio signals generated from the impedance converter to the audio output circuit of the circuit board 32, and a shielding wire for electrostatically shielding the power wire and the signal wire to provide an electrical ground (these wires are not shown in the figures).
For the adjustable gooseneck microphone, when the length of the support pipe 20 is adjusted by extending and contracting the telescopic pipe 22, the microphone cord 40 must also be extended and contracted along with the extension and contraction of the telescopic pipe 22. Therefore, a cord extension/contraction part 41 for the microphone cord 40 is provided in the output module section 30. Conventionally, the cord extension/contraction part 41 has been formed as described below (for example, refer to Japanese Patent Application Publication No. 2006-19854).
As shown in FIG. 5, the microphone cord 40 is inserted in the support pipe 20, and one end 40a thereof is connected to the condenser microphone unit 10. The other end 40b of the microphone cord 40 is, as shown in FIG. 6, pulled out into the output module section 30 after being caused to pass through the connector 23, and is soldered to an electrode terminal 32a formed on one surface of the circuit board 32.
To reduce the occurrence of noise caused by extraneous electromagnetic waves by shortening the wiring length of the microphone cord 40 in the output module section 30, the electrode terminal 32a is formed at one end close to the connector 23 side of the circuit board 32. Also, in this example, one end side of the circuit board 32 is fixed to the connector 23, for example, by soldering or screwing.
In this configuration, to provide the cord extension/contraction part 41, as shown in FIG. 6, the circuit board 32 is exposed in advance by shifting the shield case 31 to the support pipe 20 side, and as shown in FIG. 5A, the microphone cord 40 is pulled out onto the circuit board 32 in the state in which the support pipe 20 is extended to the maximum length, and is cut to an appropriate length.
Precautionary measures are taken to prevent excessive stress (force in the direction such as to break the soldered part) from being applied to the soldered part especially when the microphone cord 40 is contracted. Also, the other end 40b side of the microphone cord 40 is folded through 180 degrees and is soldered to the electrode terminal 32a so that initial creases are formed easily.
Thereafter, the shield case 31 is returned to the original position to cover the circuit board 32. The shield case 31 is screwed to the connector 23 with threads, not shown, and the output connector 33 is screwed to the shield case 31 with threads, not shown.
Thereby, as shown in FIG. 5B, when the support pipe 20 is contracted, a cord excess part corresponding to the contracted part is stored in the output module section 30 as the cord extension/contraction part 41 while being curled into a zigzag shape.
According to the above-described conventional example, since the other end 40b side of the microphone cord 40 is folded through 180 degrees and is soldered to the electrode terminal 32a of the circuit board 32 in the state in which the microphone cord 40 is extended to the maximum length, when the support pipe 20 is contracted thereafter, the other end side of the microphone cord 40 is stored in the output module section 30 while being folded into a zigzag shape. This presents problems as described below.
When the microphone cord 40 is pulled out of and brought back into the output module section 30 along with the extension and contraction of the support pipe 20, the soldered part of the electrode terminal 32a is rubbed by the microphone cord 40 each time, so that the soldered part may be broken to cause disconnection.
Also, since the microphone cord 40 tends to go straight through a narrow passage in the connector 23, it tends to curl in the direction substantially perpendicular to the board surface of the circuit board 32 (longitudinal direction) in the output module section 30.
That is to say, the microphone cord 40 is folded into a zigzag shape in a narrow space between the circuit board 32 and the inner surface of the shield case 31, so that the movement thereof becomes stiff. Therefore, the support pipe 20 is not extended and contracted smoothly. Also, excessive stress is unfavorably applied to the circuit board 32. In particular, this phenomenon appears more remarkably as the extension/contraction length of the support pipe 20 increases.
Accordingly, an object of the present invention is to provide an adjustable gooseneck microphone in which the support pipe can be extended and contracted and accordingly the extension/contraction part of microphone cord is provided in the output module section, wherein the soldered part in which the microphone cord is soldered to the circuit board is not broken by the repeated extension and contraction of microphone cord. Also, another object of the present invention is to provide an adjustable gooseneck microphone in which the movement of the extension/contraction part of microphone cord in the output module section is smooth.